The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque. Air flow into the engine is regulated via a throttle. More specifically, the throttle adjusts throttle area, which increases or decreases air flow into the engine. As the throttle area increases, the air flow into the engine increases. A fuel control system adjusts the rate that fuel is injected to provide a desired air/fuel mixture to the cylinders and/or to achieve a desired torque output. Increasing the amount of air and fuel provided to the cylinders increases the torque output of the engine.
An intake valve regulates air flow into each of the cylinders, and an exhaust valve regulates the flow of exhaust gas exiting each of the cylinders. In a cam-driven valvetrain, the intake and exhaust valves open when cam followers coupled to the valves engage lobes on a camshaft of the engine as the camshaft rotates. In some cam-driven valvetrains, a valve lift actuator adjusts which ones of the lobes the cam followers engage to adjust the amount by which the intake and exhaust valves lift from their respective valve seats when they open, which is referred to as valve lift.